The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Wet friction clutches, or more properly wet friction clutch packs, which comprise a first plurality of friction plates or discs interleaved with a second plurality of thicker reaction plates or discs connected to respective input and output members, are nearly universal components of modern multiple planetary gear automatic motor vehicle transmissions. The activation or relaxation or one or typically more than one such clutch in a predetermined sequence, steps the transmission through upshifts and downshifts.
Frequently during such operation, wet friction clutches are subjected to relatively high differential, i.e., input to output, speeds. In certain clutches and certain applications, dramatically increased spin losses have been observed when the differential speed increases beyond a certain magnitude. This non-linear spin loss increase has been attributed to instabilities of the rotating friction plates which result from gyroscopic tumbling of the plates.
The use of core plates with a shallow circumferential sinusoidal profile is state of the art for spin loss reduction at low relative (differential) speeds. However, it is believed that this approach is unsatisfactory at high relative speeds because the sinusoidal geometry essentially conforms to the first deformation mode of the plates.
There have been many other proposed solutions to this problem, all of which lead to other inefficiencies or difficulties.
The present invention is directed to an improved friction clutch configuration that reduces high differential speed instabilities and spin losses.